Water-tube boiler



July 26, 192?.

. WED. HOXIE WfXTER TUBE BOI'LER Filed Deo. 20, 1920 2 Sheets-Sheet lJul 26-1'27; v ,1636960 y ",9* w.D.Hox|E WATER. TUBE B OILER Filed Dec.250, 1920 2 sheets-sheet g E L INVENTOR ATTORNEYS Patented July 26,1927.

`Ull'fll) STATES PATENT aerien',

VJ'ILLIAM D. HOXIE, OF WESTERLY, RHOE ISLAND, ASSIGNO'R TO THE BACOCK &WILCOX COMPANY, OE BAYONNE, NEW' ERSY, A CRPORATION OF NEW JERSEY.

WATER-TUBE BOILER.

Application filed December 20, 1920. Serial No. 431,975.

My inrention relates to water tube boilers, particularly of the typeadapted for marine use.

@ne of the objects of my invention is to produce a boiler which will becompact in form and eflicient in operation. Another object of myinvention is to provide a boiler which will have a minimum tendency to'form scale if the feed water for the boiler is impure.

TWith these and other objects in view, my invention consists in theconstructions hereinafter described and specically pointed ont in thelappended claims. Y

In the accompanying drawings, Figure 1 is a front elevation, partly insection, of an illustrative form of boiler to which my present inventionhas been applied; Fig. 2 is a side elevation of the illustrative boilerwith parts of the outer wall broken away; Fig. 3 is an enlarged view ofa portion of the boiler in section to better illustrate the arrangementof some of the parts; Fig, 4 is a partial sec-tional view in thedirection of the arrows l, el of Fig. 3, and Fig. 5 is a plan view of apart of Fig. 3.

Similar reference numerals indicate' similar parts in the several views.

ln modern marine boiler practice, it is frequently desirable to providesuperheated steam. lt is also desirable that such superheated steam maybe provided eiiioien-tly without seriously departing fr'om the type ofboilers which have' come into common use for marine work. It is alsodesirable to design such boilers so that, so far as possible, the heatof the furnace will not be wasted by passing into the boiler room to thediscomfort of the operators. The boiler of the present invention isdesigned to accomplish these purposes. y

In the illustrative form of boiler, 1()v is an upper water drum and 11and 12 lower' water drums, the latter being spaced apart to accommodatea furnace chamber between them, this furnace chamber being of anydesired form and, in the instance illustrated.I being adapted 4for oilfuel, the oil being introduced through burners p'rojected through theAopenings in the furnace shown in the drawings. Each of the drums 11 and12 are connected with the upper drum by a set of water tubes 12', 13.For' reasons which will bev explained more fully hereinafter, in theform of boiler illustrated, the upper drum 10 is provided with water compartments 14, 15, which, as shown' best in Figure 2, are preferablylocated centrally crosswise of the boiler and are much shorter than thelength of the drum 10. rlhe drums 11 and 1,2 are also provided withcompartments 16, 17 which entend the entire lengthV of the lowerwaterdrums. The two rearmost rows of tubes 18, 19 are divided into threegroups of tubes, the tubes of the central group connecting` thecompartment 15 with the compartment 17 on one side of the boiler, andasimilaigroup of the set 12 connecting the compartment 1a with thecompartment 16. The remainder of the tubes of the rows 1S, 19, whichcome in front and at the rcar of the compartment 15, connect theAcompartments 16 and 17, respectively, lwith the drum' 10, this beingaccomplished kby the fact that the compartments 14; and 15 are shorterthan the length of the drum 10. l

A feed water' supplypipe 20 communi- Cates through the branchesl 21, 22with the compartments 14 and 15, respectively. The

feed water enters these compartments and passes do-wn the central tubesof the vrows 1S and 19 to the compartments 16 and 17, respectively, andfrom thence through the remainder of the tubes of these rows into themain circulation of the boiler by way of the drum 10.

At the upper portion of each set' of water tubes and on the side awayfrom the furnace chamber is a super-heater chamber which I havedesignated generally as 23, 24E. Each chamber is closed on its outerside and is open on the side adjacent the set of water tubes. ln eachchamber is a superheater which, in the form illustrated, is composedofheazders 25, 26 of the usual type, the inlet headers 26 beingconnected through the pipes 2T with the saturated steam outlet 28. Thesuperheater tubes, which areillustrated as of the U-shaped type, entendfrom the headers 25, 2G in the usual manner land lie' crosswise of thesets of tubes 12', 13 in the chan'ibers 23, 24. n i When the U-sha'pedsuperheater tubes illustrated are used, I preferably sustain the weightof thel superheater tubes and mamtain them in definite relation with thewater tubes by providing a support 29 extending upwardly from the lowerdrum beneath the superheater headers, the support 29 resting on thelower drum. At the opposite or free end, the U-tubes are supported by akind of rack 30 provided with a number of tongues adapted to extendbeneath the superheater tubes, this rack being attached to the rearmostrow of water tubes by the clamping hooks 31, the upper end of this rackbeing also fastened to the upper water drum l() by means of the strapconnection 32. The form of support shown permits a certain amount ofrelative motion in the superheater tubes, while at the same timemaintaining them in a substantially fixed relation with the set of watertubes with which they cooperate.

A baille 33 extends from the lower water drum upwardly along the set ofwater tubes and, in the form shown. behind the second row of such tubesfrom the furnace chamber. The tops of the baffles 33 are removed fromthe upper drum lO a sufficient distance to permit the gases from thefurnace chamber to flow up along the balile 33 and then enter among thewater tubes at substantially right angles thereto. At the upper ends ofthe baffles 33 are provided cross baffles 34- which extend substantiallyacross the set of water tubes and therefore to the open side of thesuperheater chamber. At the lower end of each superheater chamber ispreferably provided a second cross baille 35 which is short enough topermit the gases to pass between its low-er end and the baffle 33. Theparts are also proportioned so that the gases may pass between thebaflie 35 and the corre` spending lower water drum.

Outside of the superheater chamber and the portions of thewater tubesbelow such chambers, extend side walls 36, 37 which are removed from thesuperheater chamber and the tubes a suflicient distance to provide a gaspassage upwardly to the usual gas outlet. The walls 36 and 37 mayinsulated in the usual manner to prevent the passage of heat.

rlhe furnace gases rise along the baffles 33 and then divide with aportion passing into each of the sets of water tubes l2 and 13, in eachof which the gases first pass across the water tubes at their upper endsand then flow over the superheater tubes in a genera'lly downwarddirection into the second pass between the baffles 34, 35 and fromthence again across the tubes into the gas passage adjacentV the sidewalls 36, 37 to the gas outlet.

It will be seen that, by provi ding the baiiie 34, as shown, the gasesare forced to flow entirely over the Superheater tubes after` the gaseshave passed across the upper part of the water tubes, and that thecirculation to and from the water tubes and around the superheater tubesis positive and definite, so

that the operating conditions will not fluctuate unduly under differentconditions of service. By interposing the superheater lwith its chamberbetween the water tubes and the gas outlet, a minimum amount of heatthat might be absorbed in generating the superheated steam is permittedlto escape into the fire room through the side walls. as the spent gasesserve to assist in insulating the boiler and superheater against such aloss. The sides are in reality jacleted with the spent gases, whichserve more effectively to prevent such a radiation loss than thenon-conductive covering and casing ordinarily employed.

If desired, the baffle 35 may be omitted, and it will also be understoodthat the bafiie 33 may be placed either entirely in front of the set lofwater tubes or behind as many as is found desirable. lhile it isdesirable. for well known reasons, to provide a boiler with a double setof water tubes as illus trated, it will be understood that certain partsof my invention may be applied to a boiler having one lower water drumonly and one set of tubes. A double boiler of the type illustrated isdesirable, however, because by providing a set of water tubes and asuperheater on either side of the furnace chamber, a minimum amount ofheat is per mitted to escape into the boiler room. Suitable dust doorsand dust blowers may be provided in the several passes, as shown, tefree the tubes from dust. y

I provide the upper and lower water compartments with the arrangement ofthe water tubes connecting these compartments, hereinbefore described,in order to purify the feed water as much as possible before the feedwater enters the general circulation of the boiler. lt is well knownthat water containing certain impurities in particular' will have suchimpurities precipitated by heating the water to a relatively hightemperature. Such precipitation in itself, however, is of no advantageunless the precipitates have an opportunity to settle down and thusbecome separated from the water. The best results will be obtained byfirst heating the feed water as rapidly as possible in its journey fromthe feed water inlet into the general water circulation, so as to causeitto reach a temperature sufficiently high to cause precipitation at thebeginning of this journey, and then allowing the water to travel over arelatively long path arranged so that the precipitates may separate out,-and in which the temperature of the water 1s being gradually raised butso as not to boil, and thus agitate the water until the precipitateshave had an opportunity to settle out. The arrangement of the watertubes connectting the compartments is particularly adapted to accomplishthese ends. As the feed water passes from an upper compartment,

as l5, it crosses the first pass, .at which time the gases are stillvery hot, since they have been cooled only by crossing t-he upper partof the water tubes once; In crossing this first pass, therefore, therelatively cold feed water is raised very quickly to a. temperaturesuiiiciently high to cause precipitation. In the next portion of itsjourney downward, this water passes across the second pass in which thegases are considerably cooler' than in the first pass by reason of theirprevious passage over the superheater tubes. In the passage of thiswater across the third pass, it is contacted with the relatively coolgases which are passing' to the gas outlet. In the lower watercompartment, the water turns and flows substantially horizontally, andfrom thence upward through the remaining tubes of the rows 18 and 19. Inthese rows, the temperature of the water is .gradually raised by reasonof its passage across progressively hotter gas passages. It will benoted, therefore, that the feed water is first heated to a hightemperature and that, in its continued travel downward and thenceupward, additional heat is supplied in such a way that the temperatureof the water is raised relatively slowly, and that, by reason of thedirection of flow of the water, and

particularly its spreading out in the lower compartment, theprecipitates have full opportunity to settle out without being dis-Vturbed by the ebullition of boiling water.

For some purposes, some of the same results might be obtained by havingthe upper compartment connect with a lower compartment by a row of tubesextending entirely across the boiler, as the row 19, Vwith the lowercompartment connecting with the drum through the entire row 18 of thetubes. Such an arrangement, however, would permit atleast soine of thewater iiowing downward through the tubes 19 to return immediatelythrough the tubes 18 without remaining for any time in the compartment16 or l?, and thus not be subjected to the settling action which resultswhen the water necessarily travels horizontally in that chamber as itdoes with the arrangement which I have illustrated.

Blow-off cocks are provided both for the lower water compartments andthe lower water drums, such blow-off cocks being particularly desirableon the lower water compart-ments in order to remove the precipitateswhich may be thrown down and carried into those compartments from thefeed water.

lWhile, preferably, I form the upper and lower water compartmentsdirectly in the upper and lower water drums, respectively, it will beunderstood that such compartments may be formed independently of thesedrums.

It will also be understood that any suitable type of superheater, otherthan the U-shaped one illustrated, may be used.

I claim:

l. A steam boiler comprising an upper drum having a compartment thereinand shorter than the length of the drumy and smaller incross-sectionthan lthe cross-sec tion of the drum, a lower drum having a compartmenttherein extending longitudinally of the drum for substantially the fulllength thereof and smaller in cross-section than thel cross-section ofthe drum, a bank of water tubes arranged in rows -across the boiler,some of the tubes of one of thel rear rows of water tubes connectingsaid upper and lower compartments and the remaining tubes of said rowconnecting said lower compartment and the water space of the upper drumoutside said upper compartment, a feed water inlet for said uppercompartment, a furnace on one side of said bank of tubes, a superheateron the side of said bank opposite the furnace, said superheater havingtubes longer than the length of said upper compartment and extendingtransversly across the water tubes, and baffling arranged to direct thefurnace gasesinto and across the upper end of said bank, then across thesuperheater tubes and then again across the water tubes.

2. A steam boiler comprising an upper drum having a compartment at eachside of the vertical center line thereof, each compartment being smallerin cross-section than the drum and shorter than the length of the drum,a pair of-lower drums, spaced apart, each having a compartment smallerin crosssection than the drum and extending longitudinally of the drumrfor substantially the full `length thereof, a bank of tubes betweeneach lower drum andthe upper drum, with some of the tubes of a rear rowof tubes in each bank connecting one of the upper compartments with thelower compartment in the associated lower drum and the remaining tubesof said row connecting the lower compartment with the water space of theupper drum outside said Vupper' compartments, a furnace comprising achamber at least a portion of which `is located between said lower drumsand said banks of water tubes, aV

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